/Engine/Source/Runtime/Core/Public/Misc/PathViews.h
Check whether Parent is a parent path of Child and report the relative path if so. Case-insensitive / is treated as equal to \ Presence or absence of terminating separator (/) is ignored in the comparison. Directory elements of . and .. are currently not interpreted and are treated as literal characters. Callers should not rely on this behavior as it may be corrected in the future. callers should instead conform the paths before calling. Relative paths and absolute paths are not resolved, and relative paths will never equal absolute paths. Callers should not rely on this behavior as it may be corrected in the future; callers should instead conform the paths before calling. Examples: ("../A/B", "../A") -> (true, "B") ("../A\B", "../A/") -> (true, "B") ("../A/", "../A") -> (true, "") (".././A/", "../A") -> (false, "") ("../../../Engine", "d:/root/Engine") -> (false, "")
True if and only if Child is a child path of Parent (or is equal to it).
static bool TryMakeChildPathRelativeTo ( FStringView Child, FStringView Parent, FStringView & OutRelPath )